Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover readOnly/idempotent/non-destructive/openWorld, yet the description adds genuinely non-inferable behaviour: it costs one pull when a key is sent and zero when anonymous, it is the only tool whose answer depends on the caller's identity, and it never echoes the key. The missing piece is whether the quota counter is per-connection or per-key, which an agent tracking usage would want.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose, then usage, then behaviour, then return shape — a sensible ordering with no filler sentences. It is slightly long, and enumerating the return fields is partly redundant given an output schema exists.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter, read-only diagnostic tool, the description covers triggers, cost model, identity-dependence, and the fact that listings are absent. Return values are also structured in the output schema, so nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes no parameters, so there is nothing for the description to disambiguate and the baseline applies. The description's only parameter-adjacent content is the note that sending a key changes cost, which is useful framing rather than schema duplication.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (report) plus the exact resource set: tier, whether the key was recognised, daily quota and remainder, freshness, and upgrade location. It explicitly separates itself from pulse_jobs ('it returns no listings'), so an agent can route without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives three concrete trigger conditions (after pulse_jobs shows redacted listings, after a quota refusal, to validate a freshly configured key) and names the alternative tool for listings. This is explicit when-to-use plus when-not-to-use.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.